1. Field of the Invention
This invention relates to a dispenser pump for dispensing a liquid from a container of the type having a pump housing which can be attached to the container, a pump shaft which can be moved relative to the pump housing, especially can be manually pressed into it, a dispenser head on the pump shaft.
The term “dispenser pump” is defined especially as a metering pump or manually activated pump for delivery of liquids, such as washing lotions for cleaning the human body, body care products, cleaning products, cosmetics, but also lubricants or the like.
2. Description of the Related Art
European Patent Application EP 0 806 249 B1, upon which this invention is based, discloses a dispenser pump for delivery of liquid from a container. The pump housing can be attached to the container and holds a pump shaft which can be manually pressed into the pump housing against spring force by the user pressing on the dispenser button attached to the pump shaft. Two sleeve sections, which can be pushed into one another, serve as splash protectors and are mounted between the pump housing and the dispenser head. The reset spring is conventionally located in the pump cavity through which the liquid to be pumped flows.
Increasingly aggressive viscous liquids, especially in the form of washing lotions or the like, which are to be delivered by dispenser pumps in increasingly larger metered volumes per pump stroke, have recently been increasingly offered. In order to convey a liquid of higher viscosity with the same operating force per pump stroke and/or to convey a larger amount per stroke, a larger pump stroke is necessary. Reducing the size of the pump stroke with the result of increasing the diameter of the pump cylinder, on the other hand, would have extreme disadvantages or problems in order to be able to intake liquids or other products of higher viscosity and to deliver them with an acceptable expenditure of force.
In the known dispenser pumps, splash protection leads to a superproportional increase of the overall axial height when the pump stroke is increased. Furthermore, it is disadvantageous in the known dispenser pump that very aggressive liquids can attack the metallic reset spring or a metallic check valve.